Numerous processes are within the purview of those skilled in the art for the preparation of toners. Emulsion aggregation (EA) is one such method. Emulsion aggregation toners may be used in forming print and/or xerographic images. Emulsion aggregation techniques may involve the formation of an emulsion latex of the resin particles, by heating the monomers, using a batch or semi-continuous emulsion polymerization, as disclosed in, for example, U.S. Pat. No. 5,853,943, the disclosure of which is hereby incorporated by reference in its entirety. Other examples of emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in U.S. Pat. Nos. 5,902,710; 5,910,387; 5,916,725; 5,919,595; 5,925,488, 5,977,210, 5,994,020, and U.S. Patent Application Publication No. 2008/0107989, the disclosures of each of which are hereby incorporated by reference in their entirety.
Polyester toners exhibiting low melt properties have been prepared utilizing amorphous and crystalline polyester resins as illustrated, for example, in U.S. Patent Application Publication No. 2008/0153027, the disclosure of which is hereby incorporated by reference in its entirety.
Polyester toners have been prepared using polyester resins to achieve low melt behavior, enabling faster print speeds and lower energy consumption. However, the incorporation of these polyesters into the toner requires that they first be formulated into latex emulsions prepared by solvent containing processes, for example solvent flash emulsification and/or solvent-based phase inversion emulsification. In both cases, large amounts of organic solvents, such as ketones or alcohols, have been used to dissolve the resins, which may require subsequent energy intensive distillation to form the latexes, and are not environmentally friendly.
Solventless latex emulsions have been formed in either a batch or extrusion process through the addition of a neutralizing solution, a surfactant solution and water to a thermally softened resin as illustrated, for example, in U.S. patent application Ser. Nos. 12/032,173 and 12/056,529, the disclosures of each of which are hereby incorporated by reference in their entirety. Solventless self emulsifying granules have also been formed by melt mixing a mixture of a resin, neutralizing agent, surfactant and water as illustrated in, for example, U.S. patent application Ser. No. 12/325,396, the disclosure of which is hereby incorporated by reference in its entirety.
However, the use of water, necessary for dissolving most inorganic and solid neutralizing agents due to their high melting points, poses several operational challenges to the production of latexes and self-emulsifying granules since water injection into an extruder is challenging and may adversely affect final resin properties.
Improved methods for producing toners, which reduce the number of stages and materials, remain desirable. Such processes may reduce production costs for such toners and may be environmentally friendly.